As known, external storage devices are widely used in a variety of electronic products. Generally, an external storage device may be connected with a host through various kinds of standardized interfaces. Moreover, according to a command from the host, the external storage device performs a corresponding data accessing operation. In other words, the external storage device is operated according to a control command from the host. However, the external storage device fails to generate the control command by itself.
FIG. 1 is a schematic functional block diagram illustrating a conventional external optical disc drive. As shown in FIG. 1, the external optical disc drive 10 comprises an optical reading/writing device 16, a USB bridge circuit 14, and a USB port 12. Through a USB cable 20, the USB port 12 of the external optical disc drive 10 may be connected to a host (not shown).
For example, the optical reading/writing device 16 is a half-height type optical disc drive for a desktop computer or a slim type optical disc drive for a notebook computer.
For storing data into the external optical disc drive 10, a recordable optical disc is firstly loaded into the optical reading/writing device 16. Then, a write command is issued from the host, and a write data is transmitted from the host to the external optical disc drive 10. By the USB bridge circuit 14, the USB write command and the USB write data are converted into a SATA write command and a SATA data for example. Afterwards, the write data is recorded into the recordable optical disc by the optical reading/writing device 16.
Moreover, the optical reading/writing device 16 as shown in FIG. 1 may be replaced by a hard disc drive or a flash memory. The type of external storage device is correspondingly changed.
From the above discussions, the conventional external storage device is only able to receive the control command but does not have the host function of generating the control command.